1. Field of the Invention
The present invention relates to the field of cryptography. More particularity, the present invention relates to a cryptographic device which may be modified under regulated conditions.
2. Background Art Related to the Invention
In this country, a "regulatory" entity, typically a Federal or State agency, closely scrutinizes the exportation of cryptographic technology from a "domestic" export entity, namely an individual, partnership or corporation principally residing in the United States, to a foreign customer principally residing outside the borders of the United States. Usually, this regulatory entity requires the domestic entity to apply for and obtain an "export" license, being a form of written authorization from the regulatory entity, before being allowed to legally export cryptographic technology to the foreign customer. The available scope of the license depends on the nature of the cryptographic technology (e.g., whether its based on software or hardware, supported key length, etc.)
For example, for cryptographic software using cryptographic keys of restricted bit length usually forty (40) bits or less, the domestic entity may obtain a regional license generally referred to as a "commodity jurisdiction export license" from the regulatory entity. The commodity jurisdiction export license enables the domestic entity to legally export the cryptographic software to any number of foreign customers in a certain country or region of that country.
Besides licensing requirements, exports restrictions on the capabilities of the cryptographic technology are currently imposed by the regulatory entity. To conform to these export restrictions, the regulatory entity requires cryptographic keys to be 40-bits or less in length, even though a conventional Data Encryption Algorithm (normally referred to as "DES"), supports cryptographic keys up to fifty-six (56) bits in length. Thus, in accordance with current export restrictions, the functionality of the cryptographic technology must be substantially degraded in order for the domestic entity to obtain the export license. However, such restrictions are occasionally altered by this regulatory entity as technology advances.
One disadvantage associated with export restrictions is that they perpetuate reluctance by foreign customers to purchase cryptographic technology domestically because occasional changes in export restrictions may render previously exported technology obsolete. For example, suppose that a domestic entity sells a number of cryptographic hardware devices having 40-bit cryptographic keys to a foreign customer. A few weeks later, the regulatory entity relaxes export restrictions now allowing 56-bit cryptographic keys. Now, the foreign customer is utilizing cryptographic hardware that is obsolete and perhaps incompatible with future products. Of course, this reluctance could be mitigated by allowing a cryptographic device that is capable of being modified after manufacture.
Under current export laws, modifiable cryptographic devices may be sold only to domestic customers. The reason that modifiable cryptographic devices are not allowed to be exported to foreign customers is that these devices could be altered in the foreign countries without authorization by the regulatory entity. By providing a modifiable cryptographic device which can be modified only upon receipt of proper authorization from the regulatory entity, it may be possible to ease export restrictions on modifiable cryptographic devices. Additionally, similar to cryptographic software, the regulatory entity may be able to allow regional licenses for such modifiable cryptographic devices which would greatly reduce the costs associated with heightened regulated supervision currently required.
Additionally, restrictions on cryptographic device capabilities may be instituted even for those devices domestically distributed. For example, some cryptographic devices may require governmental regulation or a federally or state imposed "waiting" period before sales of such cryptographic devices may occur.
Hence, based on the foregoing, it would be desirable to develop and implement a cryptographic device in which its cryptographic keys and/or cryptographic algorithms could be modified only with proper authorization by an entity authorized to modify or "upgrade" the cryptographic device (hereinafter referred to as an "upgrade entity") and/or a regulatory entity as well as a method associated with such modification. Accordingly, the present invention may provide the cryptographic device as an integrated circuit component including a storing element for internally storing a public key of the upgrade entity for use in decrypting a digital signature from the upgrade entity, thus verifying that an upgrade directive originated from the upgrade entity.
The present invention may also provide the cryptographic device as an integrated circuit component including a storing element for internally storing a public key of the regulatory entity for use in decrypting a digital signature from the regulatory entity, thus verifying that the upgrade directive is authorized by the regulatory entity.
The present invention may further provide the cryptographic device as an integrated circuit component with the capability of internally generating a unique public/private key pair for potential use in performing encryption/decryption operations, securely containing and using the public/private key pair within the cryptographic device to substantially prevent detection of the key pair through reverse engineering, as well as providing a modifiable cryptographic device as a unique integrated circuit component which can remotely perform guaranteed authorized modifications.